Soil dissipation of three herbicides

Abstract

Three herbicides, trifluralin, (α,α, α‐ trifluoro‐2, 6‐dinitro‐N,N‐dipropyl‐p‐toluidine), profluralin (N‐dyclopropylmeehyl)‐α,α,α,‐trifluoro‐2, 6‐dinitro‐N‐propyl‐p‐toluidine), and dinitramine (N⁴, N⁴‐diethyl‐α, α,α‐trifluoro‐3, 5‐dinitrotoluene‐2, 4‐diamine) were incubated in an Etowah silt loam soil under laboratory conditions. The herbicides were incubated at 0.5 ppmw herbicide concentrations at 73 and 95°F, and for a time period ranging from 7 to 17 days. Three pH levels (5.3, 6.4, and 7.5) and three moisture contents (0, 50, and 100% FC) were generally used.

Maximum disappearance of each herbicide occurred at the intermediate pH of 6.4. The herbicide losses were enhanced by increasing moisture contents and increasing temperature, and time. At 7 days incubation, at 507%FC moisture and soil pH of 6.4, herbicide dissipation at 73°F was in the order: Profluralin(=30%)> Trifluralin=Dinitramine (=20%).

Key words:

• herbicide persistence
• herbicide carryover
• herbicide degradation
• pesticides